This application claims the benefit of Japanese Application No. 09-90302, filed in Japan on Mar. 25, 1997, which is hereby incorporated by reference.
1. Field of the Invention
This invention relates to a speaker apparatus and a manufacturing method thereof
2. Discussion of the Related Art
In a speaker apparatus for converting electric signals to acoustic energy, a so-called electrokinetic cone type speaker unit has conventionally been used.
FIG. 11 shows an example of such a speaker unit. Referring to FIG. 11, a cylindrical voice coil bobbin 103, around which voice coil 102 is wound, is provided at the center of a diaphragm 101 (cone) of the cone type speaker unit.
The diaphragm 101 and the voice coil bobbin 103 are fixed to one end of a ring-shaped edge 108 and a damper 109 having appropriate compliance and stiffness. The other ends of the edge 108 and damper 109 are fixed to a frame 112 equipped with a magnetic circuit 107, so that the frame 112 elastically supports the diaphragm 101 and voice coil bobbin 103.
The edge 108 and damper 109 support the voice coil 102 and voice coil bobbin 103 at respective predetermined positions in a magnetic gap of the magnetic circuit 107, which is constituted of a magnet 104, a plate 105, a pole yoke 106, and the like. With this structure, the diaphragm 101 is elastically supported without contacting the magnetic circuit 107 so as to be capable of vibrating like a piston in a predetermined direction within a predetermined amplitude range.
The leads of the voice coil 102 are connected to the respective ends of a pair of conductive lead wires 111. The other ends of the paired lead wires 111 are connected to a pair of terminals 110 provided on the frame 112.
Thus, when an electric current carrying acoustic signals is supplied from the terminals 110 to the voice coil 102 through the lead wires 111, the voice coil 102 is driven in the magnetic gap of the magnetic circuit 107 along the piston vibration direction of the diaphragm 101. As a result, the diaphragm 101 vibrates together with the voice coil 102 and voice coil bobbin 103, and converts the electric signals to acoustic energy, thereby producing acoustic waves.
A center cap 113 is fixed on the diaphragm 101 to cover a center hole at the center of the diaphragm 101, and moves integrally with the diaphragm 101. With this structure, the structural strength between the diaphragm 101 and voice coil 102 is intensified, thereby minimizing undesirable separate vibrations of diaphragm 101 and voice coil 102.
Further, because the center cap 113 vibrates integrally with the diaphragm 101, the center cap 113 also contributes to the generation of acoustic radiation power (mainly high frequency range) and also to phase correction of acoustic wave interference due to the shape of the diaphragm 101 by changing acoustic characteristics. Thus, the influences of the center hole of the diaphragm 101 on the acoustic characteristics can be corrected as desired.
The conventional electrokinetic cone speaker unit is constructed in the above manner and is manufactured by the manufacturing method shown in FIGS. 12A-12C and 13A-13D.
FIGS. 13A-13D show the manufacturing steps of the cone type speaker unit of FIG. 11. FIGS. 12A-12C show a preparatory process therefor.
First, the preparatory process will be described with reference to FIGS. 12A-12C. FIG. 12A is a cross-sectional view showing a structure of a coil gauge 114 with the preparatory process in which the coil gauge 114 is set in a frame assembly including the frame 112 and the magnetic circuit 107.
Referring to FIG. 12A, the coil gauge 114 is formed by bonding a cylindrical coil holding portion 114b, made of a resin film or the like and having a predetermined thickness, to a cylindrical surface of a main unit 114a, made of metal or the like.
The outer diameter D1 of the cylindrical surface of the main unit 114a (or inner diameter of the coil holding portion 114b) is substantially equal to the diameter of the center pole located at the center of the pole yoke 106. Accordingly, the coil gauge 114 is designed such that the coil holding portion 114b is removably fitted to the center pole of the pole yoke 106, as shown in FIG. 12C.
The outer diameter D2 of the coil holding portion 114b is substantially equal to the inner diameter D3 of the voice coil bobbin 103, as shown in FIG. 12B. Accordingly, the coil holding portion 114b is designed to hold the voice coil bobbin 103 in such a manner that the voice coil bobbin 103 can be removably fitted to the coil holding portion 114b. 
As shown in FIG. 12B, the voice coil bobbin 103, having the voice coil 102 wound thereon, is fitted to the coil gauge 114. As shown in FIG. 12C, this coil gauge 114 is fitted to the center pole of the magnetic circuit 107. This completes the preparatory process.
As a result of the preparatory process above, voice coil bobbin 103 and voice coil 102 are held in the magnetic gap of the magnetic circuit 107 without contacting the center pole of the pole yoke 106 or the plate 105. Also, the positions of the voice coil bobbin 103 and the voice coil 102 relative to the pole yoke 106 and plate 105 are determined.
The next stage of the manufacturing process will be explained with reference to FIG. 13A to FIG. 13D. First, as shown in FIG. 13A, the damper 109 is placed at a predetermined position in the frame assembly. Then, the coil gauge 114, on which the voice coil bobbin 103 and voice coil 102 have been mounted in the preparatory process explained above is inserted into the center hole of the damper 109 and fitted to the center pole of the pole yoke 106.
Next, the inner circumference and the outer circumference of the damper 109 are fixed to the voice coil bobbin 103 and the frame assembly, respectively, with an adhesive agent. Here, the leads of the voice coil 102 are extracted to the upper side of the damper 109.
As shown in FIG, 13B, the diaphragm 101 having the edge 108 attached thereto is placed on the frame assembly, and the position of the diaphragm 101, relative to the voice coil 102, is fixed. Then, the outer circumference of the edge 108 is fixed to the frame assembly and the inner circumference of the diaphragm 101 is fixed to the voice coil bobbin 103 with an adhesive agent or the like. Because the motion of the voice coil bobbin 103 is restricted by the coil gauge 114, the relative positional relationship between the voice coil 102 and diaphragm 101 remains fixed during the attachment of the diaphragm 101.
As shown in FIG. 13C, each lead of the voice coil 102 is soldered to an eyelet on the diaphragm 101. The coil gauge 114 is then removed from the voice coil bobbin 103.
Next, the center cap 113 is fixed at the center of the diaphragm 101 with an adhesive agent, as shown in FIG. 13D. On the back side of the diaphragm 101, the ends of the voice coil 102 are connected to a pair of terminals 110 through the paired lead wires 111. The cone type speaker unit is thus completed.
As described above, during the manufacture of the cone type speaker unit, the relative positions of the diaphragm 101, damper 109, and voice coil bobbin 103 need to be fixed with high precision. Therefore, until the diaphragm 101 and damper 109 are fixed to the voice coil bobbin 103 with an adhesive agent, the coil gauge 114 is necessary. For this reason, a center hole slightly larger than the maximum diameter of the coil gauge 114 at the center of the diaphragm 101 must be created.
Because the structural strength of the diaphragm 101 is reduced by this center hole, the center cap 113 normally is used to reinforce the structure. However, to form the diaphragm 101 having high stiffness with a predetermined thickness, it is preferable to form the diaphragm 101 and the center cap 113 as one piece.
The diaphragm 101 needs to have a high stiffness and to radiate acoustic waves with the same or equivalent phases throughout its entire vibrating regions without interference. To satisfy this requirement, a single-piece integrated diaphragm, such as a flat diaphragm formed of high stiffness material, has been used.
FIGS. 14A-14C show part of the manufacturing process for such a flat speaker unit using the flat diaphragm. In the figures, the same reference numerals as in FIGS. 11-13D correspond to the same or like components.
As shown in FIG. 14A, a frame 115 for the flat speaker unit is installed on the magnetic circuit 107 to constitute a frame assembly. The damper 109 is placed at a predetermined position of the frame assembly. Then, the coil gauge 114, on which the voice coil bobbin 103 and voice coil 102 have been fitted in the preparatory process illustrated in FIGS. 12A-12C, is inserted into the center hole of the damper 109 and fitted to the center pole of pole yoke 106.
The inner circumference and the outer circumference of the damper 109 are fixed to the voice coil bobbin 103 and the frame assembly, respectively, with an adhesive agent. Here, the leads of the voice coil 102 are extracted to the upper side of the damper 109.
As shown in FIG. 14B, the leads of the voice coil 102 are connected to a pair of the terminals 110 through paired lead wires 111. The coil gauge 114 is then removed from the voice coil bobbin 103 having the damper 109 fixed thereto.
Next, as shown in FIG. 14C, a flat diaphragm 117 having an edge 116 attached thereto is placed on the frame assembly and is placed at a predetermined position relative to the voice coil 102. Then, the outer circumference of the edge 116 is attached to the frame assembly with an adhesive agent, and the back side of the diaphragm 117 is attached to the voice coil bobbin 103.
Unlike the cone type speaker unit described above in this case, the flat diaphragm 117 is used, and thus, it is not necessary to reinforce the diaphragm with the center cap 113.
As described above, connection of the lead wires 111 in the flat speaker unit is carried out before the diaphragm 117 installed. In the case of the cone type speaker unit above, because the diaphragm 101 is formed to be cone-shaped, a sufficient space is provided to allow connection work of the lead wires 111 in the back of the diaphragm 101 even after the diaphragm 101 is fixed. However, if the flat speaker unit is manufactured using the same method, the diaphragm 117 is flat shaped. Therefore, a gap between the diaphragm 117 and damper 109 is much narrower, and connection work of the lead wires 111 is difficult.
However, in this type of speaker unit, as described above, the coil gauge 114 is removed and the diaphragm 117 is positioned and fixed to the voice coil bobbin 103 that is floatably supported by the damper 109 in the installation process. Thus, the voice coil bobbin 103 and diaphragm 117 can move during the installation work of the diaphragm. Therefore, they may not be fixed with a desired positional relationship.
As a result, the relative position between the voice coil 102 of the speaker unit and magnetic circuit 107 may change and/or the voice coil 102 and voice coil bobbin 103 may contact the pole yoke in a gap of the magnetic circuit 107. In such cases, electric signals supplied to the voice coil 102 cannot be efficiently converted into acoustic energy to reproduce sound.
Therefore, in the manufacture of the conventional flat speaker units, the compliances of the damper 109 and edge 116 should be limited within an appropriate range to facilitate the installation process of the voice coil bobbin 103 and diaphragm 117.
However, the compliances of the damper 109 and edge 116 need to have larger values when the low frequency reproduction range is to be expanded by lowering the minimum resonance frequency (ƒ0) of the flat speaker unit. Also, damper 109 and edge 116 need to have large compliances in order to raise the acoustic pressure of the diaphragm 117 by enlarging the vibration range (amplitude) of the voice coil 102. That is, the larger compliances are necessary to improve acoustic characteristics, such as reproduction frequency range of the flat speaker unit, maximum acoustic pressure, and the like. However, as long as the above-mentioned manufacturing method is used, there is a limit in setting of the compliances of the damper 109 and edge 116, and therefore, it is difficult to improve the acoustic characteristics of the speaker unit.
Accordingly, present invention is directed to a speaker apparatus and a manufacturing method thereof that substantially obviate the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a speaker apparatus having excellent acoustic characteristics and a simpler manufacturing method therefor.
Additional features and advantages of the invention will be set forth in the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides a speaker apparatus including a diaphragm and a magnetic circuit, wherein the diaphragm has a positioning portion for positioning the diaphragm relative to the magnetic circuit.
In another aspect, the present invention provides a speaker apparatus including a diaphragm; a magnetic circuit; and a positioning member fixed to the diaphragm for positioning the diaphragm relative to the magnetic circuit.
In another aspect, the present invention provides a method for manufacturing a speaker apparatus including the steps of fixing a magnetic circuit to a frame; positioning a coil with respect to a center pole of the magnetic circuit; connecting a damper to the coil and the frame; projecting a jig from a center hole of the center pole; engaging a positioning portion provided on a diaphragm with the jig to position the diaphragm at a predetermined position with respect to the center pole; and connecting the positioned diaphragm to the coil and the frame.
In another aspect, the present invention provides a method for manufacturing a speaker apparatus including the steps of fixing a magnetic circuit to a frame; positioning a coil with respect to a center pole of the magnetic circuit; connecting a damper to the coil and the frame; projecting a jig from a center hole of the center pole; engaging a positioning member with the jig for positioning the diaphragm at a predetermined position with respect to the center pole; fixing the diaphragm to the positioning member; and connecting the diaphragm fixed in the step of fixing to the coil and the frame.
In another aspect, the present invention provides a speaker apparatus including a frame having a magnetic circuit; a voice coil bobbin installed in the frame to be magnetically coupled to the magnetic circuit; and a diaphragm movably installed in the frame and fixed to the voice coil bobbin so as to be driven by activating the magnetic circuit, the diaphragm further having a positioning portion used for securing the diaphragm relative to the magnetic circuit during an installation of the diaphragm in the frame.
In a further aspect, the present invention provides a speaker apparatus including a frame having a magnetic circuit; a voice coil bobbin installed in the frame to be magnetically coupled to the magnetic circuit of the frame; and a diaphragm movably installed in the frame; and a support member connecting the diaphragm to the voice coil bobbin, the support member having a positioning portion used for securing a predetermined position of the diaphragm relative to the magnetic circuit during an installation of the diaphragm in the frame.
Because the present invention is so constructed as described above, the diaphragm can be securely positioned relative to the magnetic circuit. Further, the installation process of the coil and diaphragm can be carried out while the diaphragm is positioned at a predetermined position relative to the coil.
Thus, a speaker apparatus, in which the coil and diaphragm are positioned with respect to the magnetic circuit with high accuracy, can be produced easily. As compared with the conventional speaker apparatus, in which the entire diaphragm is integrally formed, the speaker apparatus of the present invention has superior acoustic characteristics.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.